<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
        <style type="text/css">
        div
        {
        position:relative; /*相对*/
        left:200px;
        /*!*right: 20px;*!   相等*/
        }
        </style>
    <script>
        // todo 判断是否 为 NaN
        var a = "abc";
        console.log(parseInt(a)); //todo NaN   Not a Number
        console.log(isNaN(parseInt(a))) // true

    </script>
</head>
<body>
<div>
<a target="_blank" href="http://www.runoob.com/js/js-type-conversion.html"> 类型互转</a>
</div>


</body>
</html>